The overall objective of this research is the production of dimer-specific antibodies and the development of sensitive assays for screening and identification of high risk, non-xeroderma pigmentosum (XP) individuals especially in families with a higher than normal susceptibility to skin carcinogenesis. Immune assays will be developed to distinguish between ultraviolet radiation (UVR)-induced thymine-thymine, thymine-cytosine, and cytosine-cytosine dimers. The antibodies specific for pyrimidine dimers will be incorporated into immune assays that will allow the rates of induction and fate of DNA damage to be measured in human lymphocytes exposed to UVR on the presumption that the risk of cutaneous carcinoma in a "normal" or non-XP population may be related to the ability to repair damaged DNA. During the first year, we have produced polyclonal antibodies from two rabbits that are specific for UVR-induced DNA damage. Binding of antibodies to irradiated DNA was measurable at antiserum dilutions of 1/10,000. These antisera have been incorporated into ELISA and flow cytometric procedures that are as sensitive as previously reported radioimmune assays for the measurement of UVR-induced DNA damage. (2)